Control system



C. 'YEOMANS CONTROL SYSTEM July 7, 1953 Filed sept. 29.A 1949 EN TOR. ,@ULS gea/man ,BY JMIOQH July 7, 1953 c. YEoMANs n 2,644,405

y CONTROL SYSTEM Filed Sept. 29. 1949 4 sheets-sheet -2 AM @wat @M c. YoMANs July 7, 1953 CONTROL, SYSTEM I Filed sept. '29, 1949 4 Sheets-Sheet 3 kalf/aww.

Gerne( y nomnvw July 7, 1953 c. Yx-:oMANs 2,644,405

CONTROL. SYSTEM I Filed Sept.- 29, 1949 l 4 Sheets-Sheet 4 Zij-4 INVENTOR.

Patented July 7, i953 2,644,405

2,644,405 ooN'rnoL `srs'rEM Charles Yeomans, Hubbard Woods, Ill., assigner to Yeomans Brothers Company, Chicago, Ill.. a corporation of Delaware application September 29, 1949,' Serial No. 118,544

Claims. (Cl. 103-238) This invention relates generally to control systems for gas displacement type ejectors and more particularly to a control systemior effecting the automatic operation of an ejector installation which comprises a plurality of interconnected gas displacement type ejectors.

In large gas displacement ejector installationsP as for example in pneumatic sewage ejector systems which are adapted to handle comparatively to provide an interlocking control arrangement for a multiple ejector or installation which not vonly prevents the `simultaneous discharge from the receiversinan automatically-controlled system, but which also permits sewage influx into any of thereceivers which are not discharging. As will hereinafter appear, the above and other objects of the invention are accomplished by the provision of a three-way, interlocking valve,

large amounts of waste material, it has been which is interconnected in the control system for found desirable to use a pair of interconnected the ejectors so as to regulate the automatic lln ejectors in preference to a single, large ejector ing and discharge operations of each ejector in of equivalent capacity. Such practice has de=I a predetermined manner. lOther objects and adveloped in part as a result oi.' the ability of the vantages of the invention will be made apparent smaller, combined ejectors to approach a more l5 in the accompanying drawings, and following nearly constant rate of sewage discharge over exdescription of onepreferred embodiment thereof. tended time periods, thereby minimizing the dif In the drawings:

nculties. incident to the discharge of sewage in Figure l is 'a sectional view of a duplex., pneularge, intermittent amounts. Duplex installamatic ejector unit which includes an automatic tions are also more reliable in operation, since the simultaneous failure of both units is very unlikely.

In order to realize the various benefits and advantages resulting from the use of a pair of ejectors in a single installation, it has been found desirable to provide control means in the automatic ejector control system which are operative to prevent the simultaneous discharge of the contentsl of the receivers of the individual ejec tors. Suitable control means for such purpose are described in the patent to E'. J. C'iabattari, No. 2,362,802, which issued November 14, 1944, and which is assigned to the assignee of this invention.

The patented control means are operative, in the eventthe sewage in the receiverA of either ejector reaches the discharge or operating'level while the other ejector is discharging, to pre- ,ceiver has been ejected. Under some conditions during such periodatherc is a possibility that the incoming sewage may accumulate in the feed lines for the receivers, and should the flow of sewage besuiiiciently large, an undesirable fbackup condition may occur onr the intake side of the installation. 'Y

It is, therefore, an object of this invention control system in accordance with the invention;

Figures 2, 3, and 4 are sectional views showing in detail the various operating positions of the control equipment during the operating cycles of the ejectors:

Figure 5 is a cross-sectional view of the pilot -valves used to e-iect general control of the operation of each of the ejector units in response to changes in the level of the material contained in the ejector receiver;

Figure 6 is an elevational view of a multiple, pneumatic ejector unit which includes an automatic control system in accordance with the invention; and v Figure 7 is a fragmentary plan view of the apparatus shown in Figure 6.

The duplex pneumatic ejector system illus" trated in the drawings includes a pair of ejector units 'l and 9 which are connected to'a common sewagefeed 1ine ll and to a common discharge line (not shown). The discharge line, in turn,

'maybe connected to a main sewer or other disposition point, in the usual manner. Each of the ejector units 1 and 9, illustrated, is of the same construction and, therefore for the purpose ofclarity, only one, the unit 1, will be described in detail. However, the elements of the unit -9 will be designated by the same reference numeral as the corresponding elements in unit 'l with the addition ofthe symbol prime The ejector unit 1 includes a receiver I3 hav= ing an inlet housing l5 and anoutlet housing Il which are provided with uni-flow valves I9 and 2|, respectively. The valves i9 and 2| are of vthe liap or swing type and insure the unidirectional floW ofthe material being moved by the connects the receiver I3 with a valve mechanism` 33 which is operable to selectively vent the receiver I3 to the atmosphere or supply it with compressed air. The valve mechanism 33 includes a housing 35 having an inlet port 3l which is connected to a source'of compressed air by a pipe line 39 and an exhaust port 4I which is connected to the atmosphere by an exhaust line 43.

The valve mechanism, 33 includes a movable piston 45 which comprises a pair of aligned, mechanically interconnected piston heads-lll and 49. The piston 45 is slidably supported ina chamber 5I in the valve housing 35 and is movable to either of two operative positions. In the iirst or air supply position (Fig. 2), the air inlet port 3'! is opened by the piston head 4l and the exhaust port 4l is closed by the piston head 119 thus supplying compressed air to the receiver I3 through the conduit 3 I .n In the second or venting position (Fig. 1), the piston head 4l covers the air inlet port 31 and the exhaust port il is uncovered by the pistonhead 39. This connects the receiver I3 to the exhaust line 43 through vthe medium of the conduit 3|. The valve mechanism 33 for the ejector unit 9 operates'in the same manner.

Control of the valve mechanisms and 33 is effected automatically'by means which is responsive to the liquid level in the individual receivers. In the illustrated unit, movement of the piston 45 to its operative positions is eiected pneumatically by a pilot valve 53 which may be of conventional construction. 'Ihe pilot valve 53 is particularly illustrated in Fig; 5 and includes a housing 55 having a chamber 5l in which is sup-ported an air -control member 59. The' member 59 is slidably supported and is adapted to be mechanically moved between two operative positions to control the distribution of compressed air which is supplied to the chamber 51 through a line 9| which is connected to the inlet port 31 of the valve mechanism 33. The base of thechamber 5T constitutes a seat for the control member 59, and a pair of air ports 63 and 65 are provided inthe seat. The location of the ports 93 and 55 and the dimensions of the member 59 are such that movement of the member 59 to either one of the operative positions will open one of the air ports' to the chamber and will permit the other of the ports to communicate with the atmosphere through a space 61 provided betweenthe central portion of the member 59 and the seat for that member.

One of the ports 63 and 95 of the pilot valve 53 is connected to each end of the chamber 5I in the valve housing 35 by conduits 69 and 1I, respectively. Movement of the member 59 to connect conduit 59 to the source of pressure air will cause an increase in pressure in the end Vof the chamber 5I adjacent the piston head 49 causingy the piston 45 to move from the position shown in Fig. 1 to the position shown in Figs. 2 and 3. The conduit 'II is ventedto the atmosphere through the space S'I so that there will not be an air lock in the other end of the chamber 5 I Slidable movement of the `control member 59 in the pilot valve 53' is eifected in response to the level of the material contained in the receiver I3. In this connection, the illustrated receiver is provided with a suitable stufng box 'i3 through which extends a shaft or rod "i5 which actuates the pilot valve 53. The lcwer end of .the rod 'I5 supports downwardly and upwardlyfacing bells TI and 19, respectively, which are arranged so that the weight of liquid in the lower bell will tend to move the rod l5 downwardly while air trapped in the downwardly facing bell 'I'I as the level of the material in the receiver I3 rises will lift the bell 19 and move the rod I5 upwardly through the stuing box 13.

The' upper end of the rod "I5 is pivotally connected by means of a link BI (Fig. 1) to one end of a lever 83 which is provided with a counterweight 85. The lever S3 is attached to a horizontally extending pivot 9'! which is offset from the center line of the lever 83, the pivot El" being rotatably supported on a casting (not shown) which isdisposed above the' rod l5. The pivot 3'! is connected to the control member 59 of the pilot valve 53 by an arm 89 (Fig.,5) Operation of the pilot valve 53' for the ejector 9 is accomplished in the same manner.

As has been previously pointed out, the exhaust port 4I and the air inlet port 3l of the valve mechanism 33 are connected to the exhaust and pressure air lines 43 and' 39, respectively. However, in order to prevent the simultaneous discharge of the ejector units 'I and 9 and to insure that one of the receivers I3 or I3 is open to receive the material to be pumped, the exhaust port 4I is connected directly to the exhaust line 43 but the air inlet port 3l of the valve mechanism 33' for the ejector unit 9 isconnected to the exhaust and pressure lines 43 and 39 by means of an interlocking control valve'9I, which may be mechanically or electrically'operated. The operation of the interlocking valve 9| is controlled by the operating cycles of the ejector I to shut-off the ilow of compressed air to the receiver I3' and to vent that receiver whenever the unit l is discharging.

In the illustrated apparatus, the interlocking control valve 9I (Figs. 1, 2, 3 and 4) is of a mechanical type and includes a valve body 93 which denes'a chamber 95 having three ports 9i, 99 and IUI. The chamber 95 is generally T-shaped and is provided with a diagonal partition ID3 which extends from a point on the valve body 93, intermediate the ports 91 and 99, to a point on the body intermediate the ports 91 and IilI as illustrated. The partition 153 in the illustrated valve `9Iv, is provided with a centrally located aperture |95, and the area around this aperture is fabricated to provide a valve seat I9?. Further, the area of the body 93 around the port 99 is Aalso fabricated to provide a valve seat I9.

In order to eect the selective interconnection of the ports 91 and IIlI and the ports 99 and IDI, a valve plunger III is disposed intermediate the seats |91 and |09. The plunger III is attached to a valve stem I I3 which is slidably supported in the body 93, a spring II5 being provided to bias the plunger III against the seat I9'Iv thereby maintaining normal communication between the ports 99 and II. The end of the valve stem I I3 is connected to a pneulnatically energized, diaphragm-type operating unit II? which, in response to an increase in pressure, will move vthe plunger III against the spring II5 to open the aperture |05 and to seal the port 99.

The interlocking control valve 9| vis vconnecte accenna into the pneumatic ejector system to v effect the desired interlocking action by connecting the port IOI to the air inlet 3l of the valve mechanism 3.3 for the ejector 9 and by connecting the ports 91 and 99 to the exhaust and pressure air line 43 and 39, respectively. These connections are made in the illustrated system by the pipe lines II9, |2I, and |23, respectiv.ely.` The diaphragm-type operating unit is connected to the conduit 3|, desirablyadjacent the valve mechanism 33, as illustrated, by aline |25.

Beforebeginning operation, the valves 25, 25', 2 9 and 29 are opened and a source of compressed air is connected to the pipe line 39. As= suming that both of the ejectors |.and 9 `are empty, the operating rods 'I5 and 1.5 will be disposed in their lowermost position substantially ,as shown in Fig. 1 under the weight of the bells I1 and 19. This will position the sliding member 59 in the pilot valve 53 in the position illustrated in Fig. 5 and the pilot valve 53 for the ejector 9 will, of course, be in the same condition. Compressed air will then now through the lines 5| into the chamber 5l in the pilot valve 53, through the port 65 in the valve seat and thence through the line 7| into the right hand end of the chamber 5| in the valve mechanism 33. The compressed air acts to move the piston 45 to the left (the position shown in Figure 1). The air displaced by the piston head 49 will flow through the line 69 and out oi the pilot valve 53 through the space provided intermediate thesliding member 59 and its seat. The action of pilot valve 53 is the same as the action of valve 53, its controlled piston 35' being in a similar position when the receiver i3 is empty. When the valve mechanisms 33 and 33' are in this position, thereceivers i3 and I3 are vented to the atmosphere through the conduits 3| .and 3| and the exhaust line 43, the air inlet ports 31 and 31' 'being covered by the piston heads 47 and 41'.

Sewage in the feed line II will then flow into receivers I3 and I3 displacing the air contained therein which air ows out through the conduits 3| and 3| and the valves 33 and 33. As the level of the sewage in the receiver rises to the level of the upper bell 'I'I or 77', the ,air trapped within the bell will move its associated rod 'I5 or I5 upwardly to shift the sliding member in the pilot valves 53 and 53.

Assuming that the receiver l5 is filled rst, the movement of the lever 83, caused by the liquid raising the bell 1l, will rotate the shaft 81 to move the sliding member 59 of the pilot valve 53 to the right in FigureV 5thereby venting the port to the atmosphere and causing the pressure air from the chamber 5l to flow into the port 63. The pressure air iiows from the port 63through the line 69 to move the piston 45 to the positionv shown in Figure 2the air displaced bythe piston head 4l lowingrto .the atmosphere through the line 7|. Themovement ofthe piston `l5 to this position lcloses the exhaust port il and interconnects the conduit 3| with the compressed air pipe line 59. The compressed air forces the sewage out of the receiver I3, and up the discharge pipe line 2l to the common discharge line, the check valves I9 and 2| insuring that the material nows in the proper direction.

As the sewage level recedes to a point which is below the rim of the lower bell 'I9 the weight of the trapped sewage will move the rod 'l5 downwardly to move the member 59 of the pilot valve 6. 53 back to its starting position (Fig. 5) `thereby returning the piston 4.5 .to .its original position and venting the compressed gas in the receiver |3 to the atmosphere through the conduit 3| and the exhaust line 53. .This discharge cycle is repeated automatically as either of the receivers I3 or I3 .is vlled with the sewage beingpumped.

When the receiver I3 of the ejector 9 is iilled, the pilot valve 53 and the valve mechanism 53' will effect similar operation of that ejector, the pressure air inlet 31 being connected to the pressure airline 39 through the pipe lines I|9 and |23 and interlocking control valve 9|. As has been pointed out, the plunger III of the interlocking control valve 9| normally closes the aperture so that the port 91 is isolated from the ports 99 and IDI. Thus, when both of the receivers I3 and I3 are filling the exhaust ports 4| and 4|' are open, the air inlet ports 3'! and 3l are c1osed..and the ejector units are free to lill.

In the event that the ejector 9 starts to dis charge while ejector 'I is iilling, pressure air will how to the port 3l of the valve mechanism 93' through the interconnected ports 99 and I9I of the interlocking valve 9|, and the ejector 9 will empty in the .manner which has been described. This condition in the system is shown in Fig. 4.

When the ejector 7 discharges its material while the receiver i3 is iilling, the pressure air is admittedl to the receiver i3 through the conduit 3| under the action of the valve mechanism 33. This pressure will act upon the diaphragmtype operating unit IIT to close port 99 of the interlocking valve 9| and to open aperture |95, thereby sealing the end of pipe line |23 and connecting pipe line II9 to the exhaust line d3 through pipe line IZI. This is shown in Fig. 2, and under these conditions the initiation of the discharge cycley in ejector 9 is prevented. Ace1 cordingly, if ejector unit l starts to discharge at any time while ejector unit 9 is lling, the ejector 9 will continue filling but cannot discharge until the ejector 1 completes its discharge cycle and the pressure in the conduit 3| is low enough to enable the spring |I5 to 'overcome the pressure of the diaphragm unit |I7.

If the ejector unit l starts to discharge while the ejector unit 9 is discharging, the pressure inF crease in the line 3| will cause the diaphragm unit I Il Ito close the port 99 and interconnect the ports 9? and lill. This condition is shown in Fig. It will be noted that the piston d5 of the valve mechanism 33 is in its normal discharging com dition, i. e. the exhaust port 1H is closed by the pist-on head. 5 9 and air inlet port 3? is con" nected to the conduit 3| ,The compressed gas in the partially emptied. receiver i3 will then be vented to the atmosphere through the line 3|. the air inlet port 3l', and the pipe lines H9 and l2! which are interconnected by the interlocking valve 9i and which thereby communicate with the exhaust pipe` linie d3. As soon as the pressure within the receiver I3 is relieved, that receiver will begin to reiill until the discharge cycle of the ejector unit is completed at which time the ejector unit 9 will be in condition to discharge.

In the described system one of the ejector units will always be in a condition to receive material from the feed line regardless oi whether or not the other unit is discharging. The interlocking means which has been described prevents simultaneous discharge of yboth ejectors. Fun thelmOle, in the described system the possibiauy of both of the units :being unable to receive ma terial due to pressure within the receivers with the accompanying backing-up of material in the ejector inlet lines is completely eliminated.

An interlocking control system embodying certain of the features of 'the invention is also adapted for use with multiple ejector installa tions, for example, the three ejector installations illustrated in Figs. 6 and "1. In this multiple ejector installation, the control system is operable to maintain one of the ejectors in condition., at all times, to receive the material being pumped. The illustrated system is so arranged that any one of the three ejector units can be removed from use for repair or maintenance while the other two units remain in operation. The operam tion of the two remaining units is controlled. in such a manner that the individual ejectors are prevented from discharging simultaneously and so that one of the units is always maintained in condition to receive the materials being pumped.

The ejector installation illustrated in Figs. 6 and '7 comprises three pneumatic ejector units 201A, 201B, and 291C. The units 201A, 201B and 201C are of the same construction and therefore only the unit 201A will be described. The indi vidual parts of the units 201B and 291C will be given reference numerals which correspond to the numerals used in designating like parts in unit 201A, with the exception that they Will carry a suix indicating the unit with which they are associated, i. e. a suix B or C instead of the suix A.

The unit 201A includes a receiver 239A which is constructed in the same manner as the receivers I3 and I3 which have been described in connection with ejector units 1 and 9. The re ceiver 201A is equipped with a pilot valve mech.- anism 2I|A which is responsive to the level oi material within the receiver, the pilot valve 2 i SA. illustrated, being of the same construction as the pilot valves 53 and 53 which have been described. The pilot Valve 2| IA is connected to an associated Valve mechanism 2I3A, by a set of three pipe lines 2 I 5A in the same manner as is employed in interconnecting the pilot valve mechanisms 53 and 53 with the valve mechanisms 33 and 33', respectively, of the ejectors 1 and 9. The valve mechanism 2 I3A is connected to the receiver 209A by a pipe line 2 I 1A.

Each of the valve mechanisms 2|3A, 2 i313, and 2|3C includes an outlet (not shown) which is connected to an exhaust line 2|9 by suitable pipe lines 22IA, 22| B, and 22IC, respectively. A shut- 01T valve is placed in each of the pipe lines 22 IA, 22 IB, and ZZIC, these valves being designated as 223A, 223B, and 223C, respectively. Each of the valve mechanisms also includes an inlet (not shown) which is connected to a pipe line 225 which is supplied with pressurized air. Specically, the inlet of the valve mechanism 2|3A is connected to one of the ports of a pneumatically operated, three-way valve 221 by means of a pipe line 229 and a shut-off Valve 23 I. Another of the ports of the three-way valve 221 is connected to the air line 225 by a nipple 233 and the other of the ports is connected to the exhaust line 2|9 by a pipe line 235.

The inlet of the valve mechanism 2|3B is connected to the pressure air line 225 by a pipe line 231 which includes a valve 239. The inlet of the valve mechanism 2|3C is connected to the pressure air line 225 through a pneumatically operated, diaphragm-type, three-way valve 24|, the connection being eiiected by a pipe line 243 and a shut-off valve 245. One of the ports of the threeway valve is connected to the pressure air line 225 and the other of the ports is connected to the exhaust line 2 I 9.

In order to effect interlocking operation, the three-way valves, 221 and 24|, and the pressure systems of the ejector units 201A, 201B, and 201C, are interconnected by suitable conduits which conduct pressure air for controlling the operation of the valves 221 and 24|. Specically, a conduit 241 is connected to the pipe line 2 |1A .of the ejector unit 201A, this conduit including a shut-oii' valve 249. The conduit 241, beyond the shut-off valve 249, is connected to the pneumatically responsive unit of the three-way interlocking valve 221 by a conduit 25| which includes a shutoff valve 253. The conduit 241 is also connected to a conduit 255 which is connected to the pipe line 2 I 1B intermediate the valve mechanism 2 |3B and the receiver 209B, a shut-orf valve 251 being disposed intermediate `the point of connection of the conduits 255 and 241 and the pipe line 2|1B. A conduit 259 connects the juncture of the conduits 255 and 241 with the three-Way interlocking valve 24|. The conduit 259 includes a shut-off valve 26| intermediate its ends.

In operation, when it is desired to use all three ejector units together, the valve 253 in conduit 25| is closed and all of the other valves are placed in the opened position. When this condition exists in the system, the inlet of each of the valve mechanisms 2 |3A and 2 3B are connected directly to the pressure air line 225 and the valve mechanism 2 I3C is connected to the pressure air line 225 through the interlocking valve 24|. The operation of the system is then controlled by the three-way interlocking valve 24| which is simultaneously operable to prevent the movement of compressed air into the receiver 209C and to connect the interior of the receiver 209C to the atmosphere whenever there is a positive pressure in either of the receivers 209A or 209B. The details of the manner of interconnection are the same as those described in connection with interlocking valve 9| associated with ejector units 1 and 9. When the system is connected in the described manner, the receiver 209C is in condition to receive the material being pumped whenever ejector units 201A and 201B are discharging.

In the event that it is desired to remove any one of the units from the system, the proper valves may be opened or closed so that the other units will operate in the manner which has been described in the units 1 and 9. The following table shows the valves which are opened and closed to eiect the operation in any desired manner.

l. To operate ejector units 201A and 201B as interlocked units with unit 201C shut down- Open valves 223A, 223B, 23|, 239, 253, 251 Close valves 223C, 245, 249, 26|

2. To operate ejector units 201A and 201C as interlocked units with unit 201B shut down- Open valves 223A, 223C, 23|, 245, 249, 26| Close Valves 223B, 239, 253, 251

3. To operate ejector units 201B and 201C as interlocked units with unit 201A shut down- Open valves 223B, 223C, 239, 245, 251, 26| Close valves 223A, 23|, 249, 253

When ejector units 201A and 201B are operated as interlocked, duplex ejectors and unit 201C is shut down, the three-way interlocking valve 221 cntrols the operation of the duplex system. Thevalve 221 is responsive to pressure' `Withinfther` ceiver 209B of the unit 201Bvso that the supply of compressed air is shutY off` from the receiver 2il9A and that receiver is simultaneously connected to the exhaust line 2 I 9u Whenever the unit 201B is discharging. Similarly, when the ejector units Z'lA and EMC are operated as interlocked units with unit 2MB shut dovvn, the interlocking valve 2M is operable to shut off the supply of compressed air to the valve mechanism 2I3C and to connect the inlet of that valve mechanism to the exhaust line in response to the discharge cycle of the unit 2iA. When units lZil'il and 291C are interlocked with unit MHA-shut down, the control valve 2M is operated in response to' the discharge cycle of the ejector unit 2MB. 1 It will be apparent that several` equivalent constructions may be employed inaccomplishing the objects of this invention'.v vFor example, in the foregoing description, the fluid-level responsive means in the receiver has been described as an inverted bell, float-type unit, other float-type units, electrically operated valves, or a combination of floats and electrically operated valves may be employed to alternately admit pressure airto the receiver and to vent it to the atmosphere. Further, the three-Way interlocking control valves have been described as pneumatic, diaphragm operated valves but it is apparent that pressure responsive, electrically controlled, three- Way valves or other types of pressure responsive pneumatic valves could be used.

Various features of the invention which are believed to be new are Set forth in the appended claims.

I claim:

1. ln apparatus oi the class described, a source of pressure air, a first and a second receiver, means connected to said receivers for delivering the material to be pumped thereto, and an outlet conduit extending from each of said receivers, a separate air conduit connecting each of said receivers to the source of pressure air, an exhaust conduit connecting each of said receivers to the atmosphere, valve means in the air conduit and the exhaust conduit for each of said receivers, said valve means for each of said receivers being responsive to the level of material within the associated receiver to alternately supply air to that receiver to discharge the contents thereof and to connect that receiver to its exhaust conduit to vent air contained in that receiver to the atmosphere thereby permitting said receiver to fill, and an interlocking valve in the air conduit of said first receiver connected in communication with said second receiver and with the atmosphere and operative during the discharging period of said second receiver to shut olf the supply of pressure air into said rst receiver and to simultaneously connect said rst receiver to said exhaust conduit for said flrst receiver.

2. In apparatus of the class described, a source of pressure air, a iirst and a second receiver, means connected/to said receivers for delivering the material to be pumped thereto, and an outlet conduit extending from each of said receivers, a

'separate air conduit connecting each of said re- 10 receiver todischarg'e the vcontents thereof andr to connect that receiver to open its exhaust conduit to vent air contained in that receiver to the atmosphere through the connected exhaust conduit thereby permitting said receiver to ll, and, an interlocking valve in the air conduit of said rst receiver connectedin vcommunication with said second receiver and YWitl'i theatrnospher'e and operative in response to the rise in pressure in said secondv receiver incident to the discharge of material therefrom to shut off the supply of pressure airv tovsaid y.rst receiver and to simultaneously @Omlect said rstlreceiverto its'cxhaust conduit. 3. Inwapparatus ofthe class described, a source f.P1?eSSl1.1 ail @.IS and ,a ,SeC0nF-,1eeVef meansconnected to said'receivers for delivering the material tgbegumrediheio, arid, an outlet tendait eriensiieeirom each 0i Seid rcivsg Separate, ailzondilii. connecting .each of@ Said re* ceivershto the source ofA pressure air, an exhaust conduit connecting each of said receivers to the atmosphere, valve means in the air conduit and the exhaust conduit of each of said receivers, said valve means for each of said receivers being responsive to the level of material within the associated receiver to alternately supply air to that receiver to discharge the contents thereof and to connect that receiver to open its exhaust conduit to vent air contained in that receiver to the atmosphere thereby permitting said receiver to nil, and an interlocking valve in the air conduit of said rst receiver, said interlocking valve having three ports, the first of said ports being connected to said source of pressure air, the second of said ports being connected to said receiver, and the third of said ports being connected to the exhaust conduit for said rst receiver, said rst and second ports being normally in communication With each other and said third port being normally'closed, and means in said interlocking valve connected in communication vvithsaid second receiverand responsive to an increase in pressure in said second receiver to seal said rst port and to eiect the intercommunication of said second and third ports.

4. In apparatus of the class described, a'source of pressure air, a first and a second receiver,

means connected to said receivers for delivering I the material to be pumped thereto, and an outlet conduit extending from each of said receivers, a separate air conduit connecting each or" said receivers to the source of pressure air, an exhaust conduit connecting each of said receivers to the atmosphere, valve means in the air conduit and the exhaust conduit of each of said receivers, said valve means for each of said receivers being responsive to the level of material Within the associated receiver to alternately supply air to that receiver to discharge the contents thereof and to connect that receiver to open its exhaust conduit to vent air contained in that receiver to the atmosphere thereby permitting said receiver to fill, and an interlocking valve in the air conduit which connects the valve means of said rst receiver with the source of pressure air, said interlocking valve having three ports, the first of said ports being connected to said source of pressure air, the second of said Aports being connected to said valveV means, and the third of said ports being connected to said exhaust conduit for said nrst receiver, said first and second ports being normally in communication whereby said valve means is connected to said source of pressure air and said third port being normally closed, and a member in said interlocking valve which is movable to seal said first port and to simultaneously effect the interccmmunication of said second and third ports, means for moving said member including a pneumatically actuated operating unit and a conduit interconnecting said operating unit with said second receiver whereby, upon an increase in pressure in said second receiver incident to the discharge of its contents, said interlocking valve member is moved to its position wherein intercommunication is effected between said second and third ports and said i'lrst port is sealed.

5. In an apparatus of the class described, a source of lpressure air, a first and second receiver, means connected to vsaid receivers for delivering the material to be pumped thereto, and an outlet conduit extending from each of said receivers, an exhaust conduit connecting each of said re ceivers to the atmosphere, a separate air conduit connecting each of said receivers to the source of pressure air, valve means at each of said air 12 conduits which is responsive to the level of material within its associated receiver to supply air to said receiver to discharge the contents thereof through said outlet conduit, and an interlocking valve in the air conduit of said first receiver ccnnected in communication with said second receiver and the atmosphere and operative during the discharge of said second receiver to shut off the supply of pressure air to said rst receiver and to vent said rst receiver to the atmosphere.

CHARLES YEOMANS.

References Cited in the file of this patent UNITED STATES PATENTS Germany June 24, 1899 

